Which of the following match is/are correct regarding B, Al, C and S elements?

Options

A. The highest first ionisation ethalpy : C
B. The largest atomic size: Al
C. The most negative electron gain enthalpy : C
D. The most metallic character: Al

Answer

To determine which of the given statements regarding the elements Boron (B), Aluminum (Al), Carbon (C), and Sulfur (S) are correct, we will analyze each statement step by step.

### Step 1: Analyze the First Ionization Enthalpy
- **Statement**: The highest first ionization enthalpy is for Carbon (C).
- **Explanation**: Ionization enthalpy generally increases across a period due to increasing nuclear charge and decreasing atomic size. Carbon, being in the second period, has a smaller atomic size compared to Boron (B) and Aluminum (Al), which are in the third period. Therefore, Carbon has the highest first ionization enthalpy among the given elements.

### Step 2: Determine the Largest Atomic Size
- **Statement**: The largest atomic size is of Aluminum (Al).
- **Explanation**: Atomic size increases down a group due to the addition of electron shells. Since Aluminum is in the third period and has more electron shells than Boron and Carbon (which are in the second period), it has the largest atomic size among the four elements.

### Step 3: Evaluate the Most Negative Electron Gain Enthalpy
- **Statement**: The most negative electron gain enthalpy is for Carbon (C).
- **Explanation**: Electron gain enthalpy is the energy change when an electron is added to an atom. Generally, non-metals like Sulfur (S) have more negative electron gain enthalpies because they are more electronegative and can stabilize the added electron better. Carbon, being a smaller atom, experiences more repulsion when an electron is added, making its electron gain enthalpy less negative compared to Sulfur. Thus, this statement is incorrect.

### Step 4: Identify the Most Metallic Character
- **Statement**: The most metallic character is of Aluminum (Al).
- **Explanation**: Metallic character increases down a group and decreases across a period. Since Aluminum is a metal and is located in the third period, it has more metallic character than Carbon and Boron, which are non-metals or metalloids. Therefore, this statement is correct.

### Conclusion
Based on the analysis:
- Statement 1 (First Ionization Enthalpy highest for C) is **correct**.
- Statement 2 (Largest Atomic Size for Al) is **correct**.
- Statement 3 (Most Negative Electron Gain Enthalpy for C) is **incorrect**.
- Statement 4 (Most Metallic Character for Al) is **correct**.

Thus, the correct matches are statements 1, 2, and 4.

### Summary of Correct Statements
- **Correct Matches**: 1 (First Ionization Enthalpy), 2 (Largest Atomic Size), 4 (Most Metallic Character).